The existing biannual regimen of fluoride varnish for young children frequently is not followed by those who present the greatest risk. The promise of new effective delivery protocols for fluoride varnish for young children has widespread implications for public health. Early childhood caries is a serious problem for preschool Hispanic and other minority children. There have been few studies identifying the frequency or dose of fluoride varnish needed to control caries in high-risk populations of young children. While semi- annual fluoride varnish applications result in small differences for high caries prevalence children, more intensive application regimens, i.e., three times a week, once a year, have been tested with older Scandinavian children and have been found to reduce caries. Such a regimen may be especially useful with low income populations that may not present themselves or be available for fluoride application months later. Our preliminary work has 1) shown that Hispanic farm worker children are at high risk for dental caries in both primary and permanent dentitions; 2) established that visits to apply chemotherapeutics such as fluoride varnish are acceptable to parents and caretakers; 3) indicated the feasibility of using fluoride varnish with this population; and 4) provided pilot one-year data of the effect of a regimen of three aplications of fluoride varnish within a 2 week period.. This study attempts to establish equivalence of the application of a massive dose regimen (3 doses in two weeks) of 50mg NaF/mL fluoride varnish (Duraflor, Pharmascience) with a semi-annual standard application of the same fluoride varnish and placebo varnish in preventing dental caries progression in Hispanic children aged 36 to 59 months. The study population will consist of Hispanic children, who are residents of Yakima County, in central Washington State. The primary end-point of the trial will be caries incidence. Caries exams assessing cavitated/nonCavitated lesions will be performed on all participants annually from baseline through year 3. The experimental design of this study is a randomized controlled clinical trial with two treatment groups and 250 participants per group.